[MC-XOBAHCK]

Вот так попробуйте скрипт исправить, будет откат к стилям прописанным по умолчанию:

function _toConsumableArray(arr) {
    if (Array.isArray(arr)) {
        for (var i = 0, arr2 = Array(arr.length);
            i < arr.length; i++) { arr2[i] = arr[i];
        } return arr2;
    }
    else { return Array.from(arr); } }
    
window.addEventListener('load', function () {
    allClass(0.4); // время transition
    function allClass(transition) {
        var question = [].slice.call(document.querySelectorAll('.question'), 0)
        answer = [].slice.call(document.querySelectorAll('.answer'), 0)
        arrayHeight = [];
        var props = function props(el) {
            return el.getBoundingClientRect();
        };
        [].concat(_toConsumableArray(question)).forEach(function (e, i) {
            arrayHeight[i] = props(answer[i]).bottom - props(answer[i]).top + 10 + 'px';
            answer[i].style.height = '0px';
            setTimeout(function () {
                return answer[i].style.transition = transition + 's';
            }, 50);
            e.addEventListener('click', function () {
                [].concat(_toConsumableArray(answer)).forEach(function (e, i) {
                    answer[i].style.height = '0px';
                    question[i].style.backgroundColor = '#fff';
                    question[i].style.color = '#000';
                });
                if (props(answer[i]).height == 0) {
                    answer[i].style.height = arrayHeight[i];
                    question[i].style.backgroundColor = '#9e39a1';
                    question[i].style.color = '#fff';
                }
                else {
                    question[i].style.backgroundColor = '';
                    question[i].style.color = '';
                };
            });
        });
    }
}, false);